Perforator with slug retaining features



Aug. 9, 1966 F. H. MUELLER ETAL 3,264,907

PERFORATOR WITH SLUG RETAINING FEATURES Filed Oct. 21, 1964 2Sheets-Sheet 1 VII/I ATTORNEYS United States Patent O 3,264,907 PERFRATRWl'ilrl SLUG RETAINING FEATURES Frank H. Mueller, Wilbur R. Leopold,Jr., Carl E. Floren, and Lynn D. Edwards, Decatur, lll., assignors toMueller Co., Decatur, lll., a corporation of Illinois Filed Oct. 21,1964, Ser. No. 405,427 8 Claims. (Cl. 77-38) The present inventionrelates to an improvement in a tool for perforating the wall o-f a pipesuch as a main or the like and, more particularly, to an improvement ina tool for cutting a slug or coupon from the wall of a main `andretaining the coupon therein so that the ycoupon does not drop down intothe main.

It it oftentimes desirable in gas distribution or other systems to tapinto a service main of a ductile metal or plastic in order that servicepipes or lines may be operatively connected to the main. Drillingmachine and closure valve assemblies have been used for this'` purpose,mounted on Ts attached to the main providing for the drilling of a holein the main through the valve and then using the valve as a permanentclosure after the drill is wllthdtrawn. Cheaper' and more simplearrangements were later provided, wherein the valve is omitted and thecutting member or perfo-rator is left in place in the T and serves as avalve to close the opening which has been cut, as shown in Patent No.2,839,075, issued to Frank H. Mueller, June 17, 1958.

An object of the present invention is to provide an improvedpertforating tool for cutting a main, the tool requiring less torque tooperate during the cutting of the coupon from the wall of the main, andbeing of the type which positively retains the coupon during the cuttingoperation so that when the tool is removed from the tapped hole in themain, the coupon is also removed completely out of the main.

Another obje-ct of the present invention is to provide an improvedcutting tool hav-ing a forwardly facing cutting surface and a minimum offrontal end area, with a reduced side contacting surface so that thereis less drag on the tool when rotary motion is applied to the toolduring cutting.

These and other objects of the present invention will appear more fullyin the following speciiication, claims, and drawings, in which:

FIGURE 1 is a vertical sectional View through a main and a service T andalso illustrating partially in vertical section and partially inelevation the improved cutting tool of the present invention in aposition after a hole has been tapped in a main;

FIGURE 2 is an enlarged fragmentary side elevational view of the cuttingtool of the present invention;

FIGURE 3 is a view similar to FIGURE 2 but with the tool of FIGURE 2rotated 90 on its axis in a counterclockwise direction looking from thetop of FIGURE 2;

FIGURE 4 is a view similar to FIGURES 2 and 3, the cutting tool beingrotated 180 with respect to FIGURE 2 and 90 with respect to FIGURE 3;

FIGURE 5 is a bottom plan view of the cutting end portion of the tool ofthe present invention taken substantially on the line 5-5 of FIGURE 4,the view being enlarged over the view of FIGURE 4;

FIGURE 6 is a view ot the cutting tool similar to FIG- URE 3 but havinga portion of the tool broken away adjacent the cutting end of the sauneto thereby illustrate the coupon retaining threads in the closed bottombore of the cutting end;

FIGURE 7 is a layout of the cutting end portion of the tool andillustrating the various surfaces of the forward facing cutting edge;and

FIGURE 8 is a fragmentary sectional view of the main dld'i PatentedAugust 9, 1966 ,and conventional serv-ice T, the view illustrating thecutting tool in elevation and having cut a coupon from the main, thecoupon being retained in the tool.

Reterring now to FIGURE 1 there is disclosed a main .10 for a duidpressure distribution system such as a gas system or the like, `a m-ainhole 12 having been tapped in the wall of the main by the removal of aslug or coupon 14. Main 10 may be made of the usual materials such assteel, plastic, or any suitable metal. A T 116 is illustrated secured tothe main l0, this particular T being made of rnet-al and welded to themain 10 when the main is made of metal. The T titting 16 is of the typedisclosed in United States Patent No. 2,839,075, issued June 17, 1958,to Frank H. Mueller. It has a body portion 17 with an interiorlythreaded through bore 18 and a lateral outlet opening 20 communicatingwith a bore 22 in a branch 24. The upper end of the main body portion 17is exteriorly threaded as indicated at 26 in order that it can receivean interiorly threaded service cap 28.

The cutting tool of the present invention is generally designated at 30and is provided with a plug-like body member 32 having a irst bodyportion 34 which is eX- teriorly threaded at 36 with threads that may bereceived in the interiorly threaded bore E18. The first body por-,tion34 has an end provided with a non-circular socket or recess 38 thereinfor receiving an Allen wrench or the like. It will now be appreciatedthat rotation of an Allen wrench in the socket 38 will cause the tool 30to advance or retract in the threaded bore 18, depending on thedirection of rotation. The body member 32 has a second body portion 40at the opposite end thereof, the second body portion 40 having adiameter on any plane therethrough normal to the axis of the body member30 which is less than the diameter of the first body portion 34. A moredetailed description of the second body portion 40 will follow later inthe specication.

Intermediate the first body portion 3l and the second body portion 40 isa cylindrical intermediate body portion 42, the intermediate bodyportion 42 having a diameter less than the diameter of the lirst bodyportion 34 and greater than any of the diameters of the body portion 40.The intermediate body portion 42 is connected to the second body portion40 by a conical shoulder 4t, the purpose of which will be describedlater in the speciiication.

The end of the second body portion 40 is provided with ta bore t6 for apurpose well known in the art, this bore having interior threads t8(FIGURE 6) to retain the cut coupon. The interior threads t8 have arelatively flat or plane root 50 between adjacent threads therebyproviding for easier reception of the coupon, the threads 48 receivingIand retaining the coupon 14 as the same is being cut by the cuttingtool 30.

The second body portion 40 comprises Ia shank portion 52 and a cuttingend portion S4 separated from the shank portion by a short cylindricalportion 56. The shank portion 52 has a back taper which is shownexaggerated in the drawings at T, the taper T being in the order ofthree-fourths of van inch per foot. The cutting end portion 54 has aforward taper T. The cylindrical portion 56 between the back taperedshank portion 40 and the forward tapered cutting end portion 54 is inthe order of three sixty-fourths of an inch so that there is a minimumof side area contact between the second body portion 40 land the wall ofthe hole 12 being cut.

As best shown in FIGURES 2 through 7, inclusive, the cutting end portion54 of the cutting tool 30 is provided with a forwardly facing ilatcutting surface 60, defined by a pair of spirally milled flat slopes 62`and 64 intersecting in a cutting point 66. The slopes 62 and 64terminate at their low side in an arcuate flat portion 68 lying in aplane normal to the axis of the body member 30. The slope 62, which is`the forward slope whenthe tool is being threaded downwardly in thethrough bore 18 to cut the coupon 14, is of a greater angle A withrespect to a plane normal to the axis of the cutting tool than is theangle B of the trailing slope 64 and, thus, as shown in FIGURE 7, thelength of the trailing slope is greater than the length of the forwardslope 62. By having the forward slope 62 at a greater angle than thetrailing slope 64 and by having only a single cutting point 66 coupledwith the taper T on the cutting end portion, the frontal area of thecutting tool 30 which is performing the cutting action for cutting thecoupon 14 from the main 10 is minimized. This reduces `the frictionalcontact and permits the coupon t be cut more cleanly and without -anysignificant amount of head being formed thereon which would interferewith the removal of the coupon. The torque required t-o rotate thecutting tool 30 and cause the cutting action is further reduced asmentioned above by providing the relatively minimum amount of surfacecontact between the wall of the hole 14 being cut and the second bodyportion of the tool member 32 because of the back taper T provided onthe shank portion 40. The surfaces 62 and 63 each occupy about 90 of thecircular end area of the cutter, while the surface 64 -occupies about180 of this end area.

To further enhance the operation of the cutting tool 30, an alkyd resinpaint having molybdenum disulfide (MOSZ) is coated on at least thesecond body portion 40 and the threads 48 of the bore 46 to act as alubricant during the cutting operation. If desired, the threads 36 ofthe first body portion 32 may also be coated. It has been founddesirable to dilute the alkyd resin paint and molybdenum disulfide 60%with a thinner when coating the threads but it has also been found thatthe cutting portion of the second body member should be coated at fullstrength or thinned only up to 20%. The molybdenum disulfide (MOS2) usedwas a commercial product manufactured by Acheson Colloid Co., PortHuron, Michigan, and known as DAG 232. While a binder of alkyd resinpaint is preferably used as it will quickly cure at room temperature,other binders for the molybdenum disulfide may be used such fas an epoxybinder.

It will be appreciated by those skilled in the art that the cutting tool30 must be made of a material which is harder than the material of themain being cut. For example, if the main is steel, the tool 30 is madeof a hardened steel which is sand blasted after the hardening operation.

The operation of the cutting tool 30 is substantially similar to theoperation described in the aforementioned United States Patent No.2,839,075. After the T 16 has been suitably secured to the main 10, theperforator tool 1s lubricated and then inserted in the T, and with thecap 2S removed, a wrench is applied to the socket 38 of the tool 30 forrotating the same. tool is then advanced by a threading action until itscutting edge engages the wall of the pipe. Further adnot only cuts thecoupon 14 from the main but the coupon is also threaded into theinteriorly threaded closed bottom bore 46. Once the coupon 14 has beencompletely severed from the main 10 and the hole 12 formed therein, thetool is rotated in an opposite direction `to the position shown inFIGURE 1 and the cap is re-applied to further seal the joint. It will,of course, be appreciated that the branch 24 will have been previouslyconnected to a service line which is desired to be tapped into the main.If it is ever de- (which has been left in the T) can then be re-threadeddown until it reaches a position where the conic-al surface 44 abutsagainst the edge of the hole 12 to thus seal off the hole 12.

It will thus be seen that the objects and advantages of this inventionhave been fully and effectively accomplished. Various changes may bemade to the specific having a first body portion adjacent the end withthe drive socket, said `first body pozrtion having exterior threadsthereon, said body member having a second body portion adjacent the endwith the closed body circular ond body portion being of reduced diametercylindrical.

4. A cutting tool as claimed in claim 1 in which said interior threadsof said closed bottom circular bore have a root portion which is fiat.

5. A cutting tool as claimed in claim 1 in which said pair of slopes ofdifferent degrees has a forward slope at a greater angle to the bodymember than the 6. A cutting tool for cutting a coupon from the wall ofthe main and for .retaining the coupon after the same is cut, saidcutting tool comprising: an elongated plug-like body member means at oneend thereof and a closed portion, said forward facing cutting edge ofsaid cutting end portion being defined by a pair of spirally arranged atslopes, one being a forward slope and the other being a trailing slope,said pair of slopes joining in a single cutting point and merging into aat arcuateV portion lying in a .plane normal to the axis of the bodymember, said forward slope having a greater angle with respect to theplane normal to the axis of the body member than said trailing slope,said closed bottom circular bore having interior threads with a flatroot portion for receiving the coupon as the same is cut from the wallof the main to thereby retain the same in the cutting tool, and at leastthe exterior surface of said second body portion and the interiorthreads of said closed bottom borre being coated with a binder havingmolybdenum disulfide therein. 7. A cutting tool as claimed in claim 6 inwhich said binder is an alkyd resin paint.

8. A cutting tool as claimed in claim 6 in which said binder is an epoxybinder.

No references cited.

G. A. DOST, Assistant Examiner.

1. A CUTTING TOOL FOR TAPPING A HOLE IN A MAIN BY CUTTING A COUPON FROMTHE WALL OF THE MAIN AND RETAINING THE COUPON AFTER THE SAME IS CUT,SAID CUTTING TOOL COMPRISING: AN ELONGATED PLUG-LIKE BODY MEMBER HAVINGA DRIVING SOCKET AT ONE END THEREOF AND A CLOSED BOTTOM CIRCULAR BORE ATTHE OTHER END THEREOF, SAID BODY MEMBER HAVING A FIRST BODY PORTIONADJACENT THE END WITH THE DRIVE SOCKET, SAID FIRST BODY PORTION HAVINGEXTERIOR THREADS THEREON, SAID BODY MEMBER HAVING A SECOND BODY PORTIONADJACENT THE END WITH THE CLOSED BODY CIRCULAR BORE, SAID SECOND BODYPORTION BEING OF REDUCED DIAMETER WITH RESPECT TO SAID FIRST BODYPORTION THROUGH ANY PLANE THEREOF NORMAL TO THE AXIS OF THE BODY MEMBERAND HAVING A FORWARD TAPERED CUTTING END PORTION AND A BACK TAPEREDSHANK PORTION WHEREBY SAID SECOND BODY PORTION HAS A MAXIMUM DIAMETER INA PLANE NORMAL TO THE AXIS OF THE BODY MEMBER IN AN AREA BETWEEN THESHANK PORTION AND THE CUTTING END PORTION THEREOF; SAID CUTTING ENDPORTION HAVING A FLAT FORWARD FACING CUTTING EDGE DE-